Drill for drilling holes in wood



Feb. 6, 1940. J. w, STOLLE 2,138,923

I DRILL FOR DRILLING HOLES IN WOOD Original Filed June 20, 1936 16 FEE-3.

A f 8 5 W////////////////// 6 I 0 W4 F5225 INVENTOR.

ATTORNEYS.

Patented Feb. 6, 1940 UNITED STATES DRILL F012; DRILLING'HOLES IN woon John William Stolle, Ashland, Maine, assignor to Charles W. Stevens, Danbury, Conn.

Original-application June 20, 1936, Serial No.

86,2441. Divided and this 26, 1938, Serial No. 236,99

3 Claims.

This application is a division of my application Serial No. 86,244, filed June 20, 1936. This invention relates to the woodworking art, and particularly to the formation of holes in textile spools and bobbin blanks and the like, and particularly to the drilling of straight deep holes having sections of dififerent diameter in elongated blanks by the use of relatively slender and flexible drills. I

In the drilling of these blanks according to conventional practice thereis a very substantial waste and loss of material due, among other things, to the *long slender drill or boring tool being deflected from its rectilinear path by the grain of the Wood which is not always parallel to the hole to-be driven. This difficulty may be largely obviated by the use of the invention of my Patent No. 1,513,350, issued October 28, 1924,

which comprises the use of a drill having a spe-' cial cutting and shaving edge and a stream of liquid, such as water or oil, to wash out the chips which are formed during the drilling operation, and to moisten and soften the wood to be bored. While the liquid step is satisfactory in some branches of the wood boring art, such as the boring of hook handles, whiflletrees, wood machine rolls, etc., I have found that in the drilling of textile spools and bobbin blanks that the oil or soap water employed has a deleterious effect upon the wood. I

One object of the invention,- therefore, is the provision of'means for utilizing compressed air and the like to blow out the chips and cuttings during the boring operation, together with the provision of a special drill which, in addition-to the patented features of my Patent 1,513,350, embodies features particularly adapted to theuse of compressed air and capable of forming a hole in a manner which is self directing and guiding along a straight rectilinear path, notwithstanding the non-parallelism of the wood grains.

A further object of the invention is a drill of the above indicated character which leaves an uncut core of wood in the center ;of the blank surrounded by a cylindrical guiding groove for assuring the straight rectilinear progress of the drill through the blank, notwithstanding the fibrous character of the wood.

For a better understanding of theinvention, reference may be had to the accompanying draw ing forming a part of this application wherein:

Figs. 1 to inclusive are diagrammatic views illustrating steps in the drilling of a blank according to the invention;

Fig.'3a isan enlarged sectional view showing the cylindrical central guiding core'and the surrounding cylindrical guiding groove formed at the bottom of the bore;

Fig. 6 is a plan view substantially enlarged of the end of the drill; and

application October ,Fig. 7 is an end view thereof.

, Referring to Figs-L to 5, I have indicated at l a textile bobbin blank or the like to be drilled and at 2' a drill according to the present invention for drilling and forming a hole 3 of the desiredv diameter in the middle section of the blank. This drill 2 forms the bore 3 to the point ,3 where it is desired to discontinue the bore of that section; I At 4 I have shown a drillwhich continues the bore throughout the blank to form a bored section 5 at one end and simultaneously therewith to ream out a section 6 of a still larger bore at the other end; the completed drilling operation being indicated in the blank of Fig. 5. The mul tiple section bore 3, 5 and 6 of the blank is formed 7 I in two operations, the drill 2 forming the bore indicated in Figs. 2 and 3 and the drill l forming the bore 5 and 6 of Fig. 5. Fig. 4 shows the sec-v ond drilling operation. The shank l of the drill 4 is of smaller diameter than the intermediate bore 3 of the blank.

I have found that by drilling the hole in the two operations by the two drillsi and 3, that the tendency of the drill to be deflected from a rectilinear path during the relative longitudinal and rotational movements of the blank and the drill is substantially reduced. I believe this due I utilized for drilling simultaneously both larger,

and smaller bore sections, namely, when the drill is engaging the wood at two or more widely separated points longitudinally of the blank. According to one aspect of the invention'the drill 2 is utilizedfor forming the intermediate'bore 3, while thedrill 4 is utilized for forming the end bores 5 and 6. The reaming part 8 of the drill i for forming the enlarged bore end 5 come into operation until the bore 5 is on its way to completion and, accordingly, the drilling operation of the two ends of the blank at this stage does not produce the same tendency to;ci.eflection as when the two operations occur at points closer to the middle section. By having the shank 1 of a smaller diameter than the bore 3 the rubbing of the shank against the walls of the bore 3 is prevented, thus removing any danger of vibration from the tip 9 of the drill, while it completes the bore 5.

For disposing of th drill progresses, I supply fluid gaseous pressure, such as air, through the passages Ill, 53 formed longitudinally of the drills. This passage or channel Ill (I 0) passes down through the tip 9 of the drill and the compressed air or other gaseuus fluid blows the chips and cuttings backwardly along the drill, namely, along the groove ll which'is formed in the side of the drill.

' As a further means for obviating deflection of does" not e chips and cuttings as the 2 the long slender drill from a straight rectilinear path, notwithstanding the departure from parallelism of the wood grain, I have, provided a drill tip 9 formed generally as indicated iii'FigsYl'to i, and as more specifically illustrated in Figs. 6 and 7. This improvement consists of forming the tip" 9 of the drill so that it will form in advance of the, bores 3 and 5 an annular groove l5 with an uncut.

core I6 surrounded by theannular groove-l5 and disposed in the axes of the bores. For this purpose I have provided the tip!) of the .drill with a relatively short pilot cutting section l1 eccentric to or ofiset from the axis 18 of the drill and bores. This pilot section H is of lesser diameterthan.

ing, as indicated at 2|) of my patent above referred to". Thus, two reaming edges 2!], 2| and three boring edges ll, II'and 22 are provided, the edges H, H of the pilot section forming a salient; The groove H in the side of the drill should be deep enough to accommodate the uncut core l6 which is formed on the axis iii of the blank and drill. This may be effected by having the sides of the groove meet at a point far enough-beyond the axis l8 to clear the core being formed; or, as is shown in Figs. 6 and "I, the drill may be provided with a central circular groove 25 to accommodate the core with the sides of the longitudinal circular groove discontinued at the groove. I

' The dimensions of the groove l5 and the uncut core l6 may be varied to suit particular requirements, but generally'the core should be of sumcient diameter and stiffness correlated with the depth of the groove iii to aid in keeping the drill concentric with the axis of the relatively rotating drill and wooden blank. I have found in practice that acore one-fourth the diameter of the bore, namely, with the core l6 one-fourth the diameter of the bore 3, is effective, with the depth of groove indicated in the drawing in guidingand causing the drill tip 9 to follow a straight rectilinear path, notwithstanding the direction of the wooden fibres and the slenderness and flexibility of the drills.

The flexing of the long slender drills is prevented according to the method of drilling above set forth. In the first drilling operation, which is performed by the drill 2, only the bore part 3 is formed, namely, a bore of one cross-section throughout and the boring is affected only at one point throughout the length of the drill, namely, at the tip 9. Accordingly, the flexing of common practice, which I believe to be due in part-to drilling two' or more different sections simultaneously, is thereby prevented or minimized. Moreover, by forming the annular groove l5 slightly in advance of the bore 3 the uncut core i6 and groove form a guide and directing means for the drill tip tending to keep it in a straight rectilinear line, namely, along the axis of the blank and notwithstanding the particular fibrous character of the wood being worked upon. When the drill 4 is introduced into the bore 3 to form the smaller section bore 5, the guiding groove 5 and the uncut-core l6 function to align and center this drill not only at the beginning of the operation but throughout the formation of the bore 5. The compressed air is supplied continuously through the passage Ill and blows out the chips and cuttings" and clearsv the end of the bore for fresh cutting operations.

The drill itself is of very small diameter and in operation the outer free end of the core is gradually and progressively broken or twisted off, due to its very small diameter.

Iv claim:

and small diameter bores in wood and with the grain thereof and having a-source. of gaseous fluid supply to remove the chips'and cuttings while the drilling proceeds, a relatively long and slender flexibleidrill for forming said bores in wood and substantiallywlth the grain thereof, said drill having a chip channel for removal of chips and cuttings, a core channel merging into said chip channel, said core channel beingof a diameter less than one third the diameter of the drill and being located in the center thereof, a cutting edge extending from the core channel to the periphery of the drill, a supply passage for supplying fluid under pressurethrough the drill, and a reame edge along the periphery of the drill.

2. For use in machines to drill relatively long and small diameter bores in wood andwith the grain thereof and having a source of gaseous fluid supply to remove the chips and cuttings while the drilling proceeds, a relatively long and slender flexible drill for forming said bores in wood and substantially with the grain thereof, said drill having-a longitudinal groove on the side thereof forming a channel for the removal of chips'and cuttings, said groove extending radially inwardly beyond'the axis of the 'drill to accommodate a small central'uncut core, a cutting edge forming the drill tip and-extending inwardly from the peripheral edge'of the drill to "a point slightly short of the axis of the drill to leave said uncut core and a supply passage for supplying flui under pressure through the drill. I 3. A relatively long and slender drill for forming bores in textile bobbins and the like, said drill having a passage to supply gaseous fluid for the drilling operation, an exit path for chips and cuttings being conveyed by said fluid, an axial opening for an uncut core formed in the drilling oper ation, a cutting face, a pilot cutting section projecting forwardly of said cutting face'and positioned eccentric to the axis or the drill,'said pilot section being adapted to cut an annular groove in advance of said cutting face and to leave an uncut core extending into said axial drill opening, a

The uncut core I5 is illustrated as of comparatively short length but in operation it may be longer.

1. For-use in machines to drill relatively long active length by substantially the radius of the hole to be formed and adapted to shave the wall of the hole.

- -JOHl lW. STOLLE. 

